Semiconductor device having a chip, reinforcing plate, and sealing material sharing a common rear surface

ABSTRACT

A plurality of chips are mounted on a substrate, coupling portions between the chips and the substrate are sealed, the chips have rear surfaces thereof collectively polished, and the substrate with the chips thereon are separated into independent semiconductor devices.

FIELD OF THE INVENTION

[0001] The present invention relates to a semiconductor device which hasa thin semiconductor element mounted thereon.

DISCUSSION OF BACKGROUND

[0002] When, in particular, a thin semiconductor element (having athickness not greater than 0.1 mm for instance) is mounted on aconventional semiconductor device, a wafer is preliminarily ground to athin one, the wafer is separated into independent chips by dicing, andthe independent chips are mounted on substrates or lead frames in ausual method.

[0003] The usual method has created a problem in that a chip is likelyto be fractured in handling, or that when a chip is mounted on asubstrate, a stress is generated by bonding electrode portions to damagea coupling portion or the semiconductor element.

SUMMARY OF THE INVENTION

[0004] It is an object of the present invention to solve the problem,and provides a semiconductor device having a thin semiconductor elementmounted thereon, the semiconductor element being obtained by mounting aplurality of chips on a substrate before thinning the thickness of thechips, and polishing rear surfaces of the chips with coupling portionsprotected by sealing after, e.g. testing or repairing or with a stressto the chips lessened.

[0005] According to a first aspect of the present invention, there isprovided semiconductor device having a thin semiconductor elementmounted thereon, the semiconductor element being obtained by mounting aplurality of semiconductor elements on a substrate, polishing rearsurfaces of the semiconductor elements after sealing coupling portions,and separating the substrate with the semiconductor elements thereoninto independent semiconductor devices.

[0006] According to a second aspect of the present invention, areinforcing plate is fixed on the substrate, and the substrate with thesemiconductor elements thereon are separated into the independentsemiconductor devices after assembly.

[0007] According to a third aspect of the present invention, areinforcing plate is fixed on the substrate, the reinforcing platecomprising a metallic plate and a wiring plate in layered fashion, andconduction is made between the wiring plate and wiring on the substrate.

[0008] According to a fourth aspect of the present invention, there isprovided a semiconductor device having thin semiconductors elementmounted thereon, the semiconductor elements being obtained by mounting aplurality of semiconductor elements, sealing the semiconductor elements,providing a laminate on rear surfaces of the semiconductor elements toform a wiring layer with the semiconductor elements included thereinafter polishing the rear surfaces of the semiconductor elements, andwiring, followed by repeating the same step.

[0009] The present invention is constructed as stated earlier, offeringthe following advantages.

[0010] In accordance with the first aspect, the plural semiconductorelements are mounted on a substrate, and the rear surfaces of thesemiconductor elements are polished after sealing. As a result, thesemiconductor elements can be made thin without damaging thesemiconductor elements.

[0011] In accordance with the second aspect, the reinforcing plate isfixed on the substrate. Even if the substrate has low rigidity, thesubstrate can ensure required flatness, allowing polishing of the rearsurfaces to be carried out with good precision.

[0012] In accordance with the third aspect, the reinforcing plate isfixed on the substrate, and conduction is made between the wiring plateand the wiring on the substrate. Thus, the semiconductor device canimprove a wiring allowance for the substrate, can have a thinsemiconductor element mounted thereon, and the semiconductor element canbe made smaller.

[0013] In accordance with the fourth aspect, semiconductor elements aremounted, the semiconductor elements are sealed, a wiring layer isprovided by laminating after polishing rear surfaces of thesemiconductor elements, and followed by the repeating the same step.This arrangement can provide a semiconductor device with a plurality ofchips mounted thereon in high density.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A more complete appreciation of the invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

[0015]FIG. 1 is a cross-sectional side view showing the semiconductordevice according to a first embodiment of the present invention;

[0016]FIG. 2 is a fabrication flowchart for preparing the semiconductordevice according to the first embodiment;

[0017]FIG. 3 is a cross-sectional side view showing the semiconductordevice according to a second embodiment of the present invention;

[0018]FIG. 4 is a fabrication flowchart for preparing the semiconductordevice according to the second embodiment;

[0019]FIG. 5 is a cross-sectional side view showing the semiconductordevice according to a third embodiment of the present invention;

[0020]FIG. 6 is a cross-sectional view showing the semiconductor deviceaccording to a fourth embodiment of the present invention, and

[0021]FIG. 7 is a fabrication flowchart for preparing the semiconductordevice according to the fourth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Now, preferred embodiments of the present invention will bedescribed in detail, referring to FIGS. 1 through 7.

EMBODIMENT 1

[0023] In FIG. 1 is shown a cross-sectional side view of thesemiconductor device according to a first embodiment of the presentinvention. In FIG. 1, reference numeral 1 designates a thin chip as asemiconductor element, which has been polished thin, reference numeral 2designates a substrate, reference numeral 3 designates a bump, whichcouples the thin chip 1 and the substrate 2, reference numeral 4designates a sealing resin, and reference numeral 5 designates anexternal terminal provided on the substrate 2.

[0024] In FIG. 2 is shown an example of the fabrication flowchart forpreparing the semiconductor device shown in FIG. 1. As shown in FIG. 2,a plurality of chips 1 are mounted on the substrate 2 (Step S1),coupling portions between the substrate 2 and the chips 1 are sealed(Step S2), and then the chips 1 have rear surfaces thereof collectivelyground (Step S3), and the substrate with the chips thereon is separatedinto independent semiconductor devices (Step S4).

[0025] As explained, in accordance with the semiconductor device and thefabrication method of the first embodiment, the rear surfaces of thechips 1 can be ground thin without damaging the chips 1 or the bumps 3as the coupling portions. The collective grinding of the rear surfacescan increase productivity.

EMBODIMENT 2

[0026] In FIG. 3 is shown a cross-sectional side view of thesemiconductor device according to a second embodiment of the presentinvention. In FIG. 3, reference numeral 6 designates a reinforcingplate, which is fixed on the substrate 2. The other elements are thesame as those of the first embodiment.

[0027] In FIG. 4 is shown an example of the fabrication flowchart forpreparing the semiconductor device according to the second embodiment.As shown in FIG. 4, a plurality of chips 1 are mounted on the substrate2, (Step S11), reinforcing plates are fixed on the substrate (Step S12),the coupling portions between the chips 1 and the substrate 2 are sealed(Step S13), the chips 1 have rear surfaces thereof polished (Step S14),and then the substrate 2 with the chips thereon are separated intoindependent semiconductor devices (Step S15).

[0028] As explained, the semiconductor device and the fabrication methodaccording to the second embodiment can ensure the flatness of thesubstrate and polish the rear surfaces of the chips with good precisioneven if the substrate has low rigidity.

EMBODIMENT 3

[0029] In FIG. 5 is shown a cross-sectional side view of thesemiconductor device according to a third embodiment of the presentinvention. In FIG. 5, reference numeral 6 designates a reinforcingplate, which comprises a metallic plate 8 and wiring plates 7 inthree-layered fashion. Reference numeral 10 designates a wire forelectrical conduction between the reinforcing plate 6 and the substrate2. Although the reinforcing plate 6 has such a three-layered structureof the wiring plate 7/the metallic plate 8/the wiring plate 7 in thethird embodiment, the layered structure or the order of the plates inthe layered structure is not limited to the shown fashion.

[0030] As explained, the semiconductor device according to the thirdembodiment can improve the wiring allowance for the substrate and canhave thin semiconductor elements mounted thereon in a smaller size.

EMBODIMENT 4

[0031] In FIG. 6 is shown a cross-sectional side view of thesemiconductor device according to a fourth embodiment of the presentinvention. In FIG. 6, reference numeral 20 designates a wiring layer,which is layered on the substrate 2, and which include chips 1 in pluralsublayers. Reference numerals 15, 16 and 17 designate the respectivewiring sublayers.

[0032] In FIG. 7 is shown an example of the fabrication flowchart forpreparing the semiconductor device according to the fourth embodiment.The wiring layer 20 shown in FIG. 6 is prepared by coupling chips 1(Steps S21 and S26), sealing (Step S22), polishing the rear surfaces ofthe chips (Step S23), providing a laminate on the rear surfaces (StepS24), and wiring (Step S25), repeating these steps, and finallyseparating the substrate with the wiring layer thereon into independentsemiconductor devices as shown in the flowchart of FIG. 7.

[0033] As explained, the semiconductor device and the fabrication methodaccording to the fourth embodiment can provide a semiconductor devicewith plural thin chips mounted thereon in high density.

What is claimed is:
 1. A semiconductor device having a thinsemiconductor element mounted thereon, the semiconductor element beingobtained by mounting a plurality of semiconductor elements on asubstrate, polishing rear surfaces of the semiconductor elements aftersealing coupling portions, and separating the substrate with thesemiconductor elements thereon into independent semiconductor devices.2. The semiconductor device according to claim 1, wherein a reinforcingplate is fixed on the substrate, and the substrate with thesemiconductor elements thereon are separated into the independentsemiconductor devices after assembly.
 3. The semiconductor deviceaccording to claim 1, wherein a reinforcing plate is fixed on thesubstrate, the reinforcing plate comprising a metallic plate and awiring plate in layered fashion, and conduction is made between thewiring plate and wiring on the substrate.
 4. A semiconductor devicehaving thin semiconductors element mounted thereon, the semiconductorelements being obtained by mounting a plurality of semiconductorelements, sealing the semiconductor elements, providing a laminate onrear surfaces of the semiconductor elements to form a wiring layer withthe semiconductor elements included therein after polishing the rearsurfaces of the semiconductor elements, and wiring, followed byrepeating the same step.